Update values for currency migrations fix

What does this commit/MR/PR do?

- Update values for currency migrations fix
- Fix for issue `saleor/saleor#3235 by PR
`saleor/saleor#3506

Why is this commit/MR/PR needed?

- The currency migrations prior to this would break

deployment/helm/values.yaml

@@ -141,7 +141,7 @@ saleor:
     mediaUrl: /media/
     enableSilk: false
     defaultCountry: IE
-    defaultCurrency: USD
+    defaultCurrency: EUR
     availableCurrencies:
       - AUD
       - CAD